The Virology Core involves laboratories both in Chile and Panama. All virological core services required to support projects 1-3 in Chile are fully operational. Personnel trained during the initial ICIDR grant are in place and assays have been validated. They are executed now on a routine basis. A new BSL-3 laboratory has just been completed at Catholic University (PUC) and another at Development University (UDD) will be ready by June 2005. Western strip immunoblot assays (SIAs) for specific IgM and IgG to diagnose Andes virus infection in humans are now run at clinical centers in the nine geographic regions of Chile where HCPS occurs. Antigens are prepared and supplied by PUC. Thus diagnosis of disease for the purpose of enrollment of patients in projects 2 and 3 does not have to wait for answers in laboratories in Santiago. Indeed, these regional centers now perform diagnostic services for other medical centers in each region as a public health service. Real time quantitative RT-PCR is now available to make early diagnoses of Andes virus infection before the onset of clinical illness and to quantitate viral burden in distinct body fluids of patients. The latter method also will be utilized for rodent infections in project 1. HLA typing of patients who suffer HCPS is ongoing in the UDD laboratory. Neutralizing antibody assays have been developed for both Andes (in Chile) and Choclo (in Panama) viruses and the former will be used to guide treatment trials using immune plasma in Chile beginning in year 2. The Choclo test will be important in further investigation of human infection versus clinical disease in Panama. A novel restriction fragment length polymorphism assay has been developed in the Panama core laboratory that clearly distinguishes Choclo and Calabazo infection in rodents. It will be important in furthering ecologic investigations involving these two hantaviruses for project 1.